The present invention relates to a turret milling machine, and more particularly to a driving head holder therefor.
The conventional driving head holder, as shown in FIGS. 1 & 2, for a turret milling machine includes a driving head holding member 1 having 3 through arcuate grooves 111 and a central through hole 112, a cantilevering coupling member 4 having two side walls 41, 42 respectively having large holes 411, 421 and small holes 412, 422, a bolt 12 penetrating through holes 411, 412 & 421 for pivotably mounting member 1 between side walls 41, 42 three bolts 11 respectively passing through holes 412, 422 and grooves 111 for fixing member 1 against side walls 41, 42, a worm rack 15 provided on holding member 1, and a worm 5 mounted on member 4 and meshing with rack 14 for adjusting the pivoting degree of member 1 with respect to member 4. Such driving head holder has the disadvantage that long bolts 11 cannot effectively securely fix member 1 against side walls 41, 42 or that member 1 relatively easily pivots with respect to member 4 during a working period of the milling machine.
In order to overcome the above shortcoming, it is proposed that the driving head holder, as shown in FIGS. 3 & 4, includes a driving head holding member 6 having two side wall 61, 62 with side wall 61 being provided with a worm rack meshing with worm 5, a cantilevering coupling member 7 having two side walls 73, 74, a large mounting bolt, and 8 small mounting bolts 14 respectively bolting side walls 61, 62 against side walls 73, 74. Although this latter holder overcome the disadvantage suffered by the former holder, it suffers from the disadvantages that the stiffness of holding member 6 is much smaller than that of holding member 1 and that worm 5 merely meshes with side wall 61 so that an asymmetrical situation easily occurs between side walls 61, 62 which results in that there is a vibrating phenomenon during the working period.